CTS Power, Grounding, and Electrical Safety

Question 1

What is the primary purpose of a technical ground (also called a 'clean ground' or 'audio ground') in an AV system rack?

Accepted Answer

To establish a low-impedance, low-noise reference point that reduces hum and interference in audio/video signals

Answer

To provide a path for fault current to trip circuit breakers

Answer

To equalize the voltage between the positive and negative supply rails

Answer

To dissipate static electricity from technicians touching equipment

Question 2

A 'ground loop' in an AV system most commonly manifests as which symptom?

Accepted Answer

A 60 Hz (or 120 Hz) hum in audio and/or horizontal bars rolling through a video image

Answer

Complete loss of video signal

Answer

Random digital dropouts in HDMI signals

Answer

Overheating of power amplifiers

Question 3

When calculating the load for a 20-ampere, 120-volt circuit in an AV rack, the NEC (National Electrical Code) recommends limiting continuous loads to what percentage of the circuit's rated capacity?

Accepted Answer

80%

Answer

100%

Answer

90%

Answer

50%

Question 4

What does a power conditioner provide that a basic surge protector does not?

Accepted Answer

Line conditioning including EMI/RFI filtering and voltage regulation to clean AC power

Answer

Higher ampere capacity for large power amplifiers

Answer

Ground fault circuit interruption (GFCI) protection

Answer

Automatic transfer to battery backup during outages

Question 5

What safety hazard does the 'one-hand rule' address when working on powered electrical equipment?

Accepted Answer

Preventing current from passing across the chest by keeping one hand away from grounded surfaces

Answer

Dropping tools into live equipment by using both hands simultaneously

Answer

Avoiding repetitive strain injury by alternating hands during installation

Answer

Ensuring one hand is always free to operate a fire extinguisher

Question 6

An AV rack contains equipment totaling 2,400 watts of continuous load. Using the NEC 80% rule, what is the minimum circuit capacity needed to power this rack safely from a single 120V circuit?

Accepted Answer

30 amperes

Answer

20 amperes

Answer

25 amperes

Answer

15 amperes